1. Field of the Invention
This invention relates, generally, to bailers. More particularly, it relates to a bailer that has a valve assembly at its lowermost end that seals effectively against leakage when seated.
2. Description of the Prior Art
Bailers are elongate cylindrical tubes that are lowered into containers for liquid fluids, bodies of water, and the like for the purpose of taking a sample of the liquid fluid so that laboratory tests can be performed thereon.
In the industry standard bailer, a free-floating ball valve at the lower end of the bailer unseats from its valve seat when the bailer is lowered into a liquid fluid, i.e., as liquid fluid flows upwardly into the hollow interior of the bailer. The ball valve travels downwardly into seating relation to its valve seat when the bailer is lifted upwardly from the liquid fluid. When properly seated, the ball valve should substantially prevent leakage of the liquid fluid from the hollow interior of the bailer.
In practice, however, the ball valve leaks profusely. The clothing of the person carrying the bailer to a vehicle that will transport the collected sample to a lab often gets wet as the liquid fluid within the bailer leaks past the ball valve. If the liquid fluid is an acid or other irritant, the leakage is more than a mere nuisance. Even if the liquid fluid is just water, the loss of sample is undesireable.
The seat for the ball valve is an annular step formed on an interior surface of a frusto-conical wall that defines the lowermost end of the bailer. A single grain of sand on the annular step can defeat proper seating of the ball valve. Sand and other particles are commonly found in the liquid fluids that are collected by bailers in the field.
What is needed, then, is an improved valve assembly at the lowermost end of a bailer. The improved valve assembly would not be defeated by a single grain of sand and would not be rendered ineffective by even relatively large amounts of sand.
However, it was not obvious to those of ordinary skill in this art how a leak-inhibiting valve could be provided, in view of the art considered as a whole at the time the present invention was made.